Column 4 of triangle A152798; a(n) = A152798(n+4,4).

Terms

a(0) =1a(1) =1a(2) =5a(3) =15a(4) =49a(5) =180a(6) =685a(7) =2748a(8) =11683a(9) =52262a(10) =245357a(11) =1207538a(12) =6217803a(13) =33428738a(14) =187323142a(15) =1092328063a(16) =6618105311a(17) =41600580908a(18) =270931087106